The present invention relates generally to peritoneal dialysis. More specifically, the present invention relates to peritoneal dialysis solutions.
It is known to use dialysis to support a patient whose renal function has decreased to the point where the kidneys no longer sufficiently function. Two principal dialysis methods are utilized: hemodialysis; and peritoneal dialysis.
In hemodialysis, the patients blood is passed through an artificial kidney dialysis machine. A membrane in the machine acts as an artificial kidney for cleansing the blood. Because it is an extracorporeal treatment that requires special machinery, there are certain inherent disadvantages with hemodialysis.
To overcome the disadvantages associated with hemodialysis, peritoneal dialysis was developed. Peritoneal dialysis utilizes the patient's own peritoneum as a semi-permeable membrane. The peritoneum is the membranous lining of the abdominal cavity that due to a large number of blood vessels and capillaries is capable of acting as a natural semi-permeable membrane.
In peritoneal dialysis, a dialysis solution is introduced into the peritoneal cavity utilizing a catheter. After a sufficient period of time, an exchange of solutes between the dialysate and the blood is achieved. Fluid removal is achieved by providing a suitable osmotic gradient from the blood to the dialysate to permit water outflow from the blood. This allows the proper acid-base electrolyte and fluid balance to be returned to the blood and the dialysis solution is simply drained from the body cavity through the catheter.
Although many advantages to peritoneal dialysis exist, one of the difficulties that has been encountered is providing a suitable amount of osmotic agent. What is required is achieving a sufficient osmotic gradient. The osmotic agent is used in a dialysis solution to maintain the osmotic gradient that is required to cause the transport of water and its accompanying toxic substances across the peritoneum into the dialysis solution.
Using dextrose as an osmotic agent is known. Dextrose is fairly safe and is readily metabolized if it enters the blood. However, one of the issues with respect to dextrose is that due to its small size, it is rapidly transported from the peritoneal cavity. Because dextrose crosses the peritoneum so rapidly, the osmotic gradient is dissipated within two to three hours of infusion, leading to the loss of ultrafiltration.
A disadvantage of the rapid uptake of glucose by the blood is that it can represent a large proportion of the patient's energy intake. With respect to, for example a diabetic patient, this can represent a severe metabolic burden to a patient whose glucose tolerance is already impaired. Dextrose can also cause problems with respect to hyperglycemia and obesity.
Typical peritoneal dialysis solutions contain sodium in a concentration of 132 mEq/L and dextrose at a concentration of 1.5 to 4.25% by weight. The solutions rely on a high initial solution osmolality to affect the transport of water (metabolic waste products) from the circulation to the peritoneal cavity. Such a solution results in a daily absorption of 150 to 300 grams of glucose from the dialysate in the typical peritoneal dialysis patient.
Further, with respect to the sodium levels, most hypertensive end stage renal patients are volume and sodium overloaded. Current peritoneal dialysis solutions do not adequately control blood pressure, because among other things they do not remove enough sodium. Still further, an issue arises with respect to fluid intake because renal patients must control their fluid intake.
Therefore, a need exists for an improved peritoneal dialysis solution.